NetBSD/emips port committed (Update #2)
I've mentioned
this
in the past, and it's in the official tree now - citing
from Antti Kantee's
posting:
``I have just committed support for the Extensible MIPS ("eMIPS") platform.
The NetBSD/emips port runs on Xilinx and Beecube FPGA systems and the
Giano system simulator.

eMIPS is a platform developed at Microsoft Research for researching
reconfigurable computing. eMIPS allows dynamic loading and scheduling
of application-specific circuits for the purpose of accelerating
computations based on the current workload.

NetBSD eMIPS support for NetBSD 4.x was written at Microsoft Research
by Alessandro Forin and Neil Pittman. Microsoft Corporation has
donated full copyright to The NetBSD Foundation.

Platform support for eMIPS is the first part of Microsoft's
contribution. The second part includes the hardware accelerator
framework and will be proposed on tech-kern soon.''

Update #2:
Antti was so kind to point me at the paper published by the people
behind NetBSD/emips, titled
An online scheduler for hardware accelerators on general- purpose operating systems:
``This paper presents an online scheduling algorithm for hardware accelerators and its implementation on the NetBSD operating system. The scheduler uses the current performance characteristics of the accelerators to select which accelerators to load and unload. [...] The NetBSD modifications consist primarily in loadable kernel modules, with minimal changes to the operating system itself.''.
Secion 7 goes into details WRT NetBSD and the (LKM based) kernel modules..